Shoulder arthroplasty system

ABSTRACT

An implant system for total shoulder arthroplasties, hemi shoulder arthroplasties, and “reverse” total shoulder arthroplasties including a humeral stem having an enlarged head portion with interfaces adapted to removably receive various modular interchangeable components, such as articulating liners, spacers, and adapter inserts. The humeral stem functions as a universal platform that may be used in either conventional or “reverse” total shoulder arthroplasties, as well as hemi shoulder arthroplasties, and may remain implanted in place during a revision in which the implant system is converted between the foregoing configurations, for example.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under Title 35, U.S.C. § 119(e) ofU.S. Provisional Patent Application Ser. No. 60/760,897, entitledSHOULDER ARTHROPLASTY SYSTEM, filed on Jan. 20, 2006 and U.S.Provisional Patent Application Ser. No. 60/805,012, filed on Jun. 16,2006, entitled SHOULDER ARTHROPLASTY SYSTEM, the entire disclosures ofwhich are expressly incorporated by reference herein.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to surgical implant systems, includingimplants, instruments, and methods for performing a total shoulderarthroplasty, a hemi shoulder arthroplasty, or a “reverse” totalshoulder arthroplasty.

2. Description of the Related Art

In a healthy shoulder, the proximal humerus is generally ball-shaped,and articulates within a socket formed by the scapula, called theglenoid, to form the shoulder joint. Conventional implant systems forthe total replacement of the shoulder joint due to disease or trauma,i.e., a total shoulder arthroplasty, generally replicate the naturalanatomy of the shoulder, and typically include a humeral componenthaving a stem which fits within the humeral canal, and an articulatinghead which articulates within the socket of a glenoid componentimplanted within the glenoid of the scapula. An implant system for thereplacement of only the humeral component of the shoulder joint, i.e., ahemi shoulder arthroplasty, typically includes only a humeral componentwhich articulates within the natural glenoid socket of the scapula.

Recently, “reverse” type implant systems have been developed in whichthe conventional ball-and-socket configuration that replicates thenatural anatomy of the shoulder is reversed, such that a concaverecessed articulating component is provided at the proximal end of thehumeral component that articulates against a convex portion of theglenoid component. Such reverse shoulder implant systems are thought toprovide an increased range of motion for treatment of glenohumeralarthritis associated with irreparable rotator cuff damage, for example,by moving the center of rotation between the humeral component and theglenoid component to allow the deltoid muscles to exert a greater leverarm on the humerus.

SUMMARY OF THE INVENTION

The present invention provides an implant system for total shoulderarthroplasties and hemi shoulder arthroplasties, including a humeralstem having an enlarged head portion with interfaces adapted toremovably receive various modular interchangeable components, such asarticulating liners, spacers, and adapter inserts. The humeral stemfunctions as a universal platform that may be used in eitherconventional or “reverse” total shoulder arthroplasties, as well as hemishoulder arthroplasties, and may remain implanted in place during arevision in which the implant system is converted between the foregoingconfigurations, for example. The articulating liner articulates againsta glenoid component, and may be angled to change the neck angle of thehumeral stem from an angle suited for a conventional total arthroplastyor a hemi arthroplasty to an angle suited for a “reverse” totalarthroplasty. The spacer may optionally be used to fit between thehumeral stem and the articulating liner to provide increased jointtension when needed. The adapter insert is used to provide an interfacewith a convex articulating component in a hemi arthroplasty application.A glenoid component is also provided which is mountable to the glenoidby a plurality of polyaxial locking screws, and which receives aglenosphere having a smooth, convex and uninterrupted articulatingsurface against which the articulating liner of the humeral componentmay articulate.

In one form thereof, the present invention provides a humeral implantcomponent for use in a total shoulder arthroplasty or a hemi shoulderarthroplasty, including a stem portion extending toward a distal endthereof; a head portion at a proximal end thereof, the head portionincluding an internal cavity having first engagement structure and afirst tapered bore; and a second component received within the internalcavity and including a first stem received within the first taperedbore.

In another form thereof, the present invention provides a humeralimplant component for use in a total shoulder arthroplasty or a hemishoulder arthroplasty, including a stem portion defining a longitudinalaxis; and a head portion having first engagement structure, and aportion which defines a first angle with respect to the longitudinalaxis, the first angle between about 35 and about 55 degrees.

In another form thereof, the present invention provides a humeralimplant component for use in a total shoulder arthroplasty or a hemishoulder arthroplasty, comprising a stem portion defining a longitudinalaxis; and a head portion having first engagement structure, and asurface which defines a first angle with respect to the longitudinalaxis; and a second component separate from the stem and secured to thefirst engagement structure, the second component having a second surfacedefining a second angle between the first surface and the secondsurface.

In another form thereof, the present invention provides a humeralimplant component for use in a total shoulder arthroplasty or a hemishoulder arthroplasty, including a stem portion defining a longitudinalaxis; and a head portion having first engagement structure; and a secondcomponent separate from the stem and secured to the first engagementstructure, the second component having a surface defining one of ananteversion angle and a retroversion angle with respect to thelongitudinal axis of between about 1 and about 30 degrees.

In another form thereof, the present invention provides a humeralimplant component for use in a total shoulder arthroplasty or a hemishoulder arthroplasty, including a stem portion extending toward adistal end thereof; and a substantially enlarged head portion at aproximal end thereof, the head portion including a suture grooveadjacent the proximal end.

In another form thereof, the present invention provides a glenoidimplant component for use in a total shoulder arthroplasty, including abody having a stem extending from a medial side thereof; at least onehole in the body including a substantially convex seat therein; at leastone screw extendable through the hole, the screw including a threadedshank and an at least partially spherical head, the head abuttableagainst the seat; and a screw retainer movable between a first positionwherein the screw head may move polyaxially with respect to the seat anda second position wherein the screw head is retained in a fixed positionwith respect to the seat.

In another form thereof, the present invention provides a glenoidimplant component for use in a total shoulder arthroplasty, including abase member, including a substantially cup-shaped body having a basewall; and a tapered annular wall extending from a lateral side of thebase wall; and an articulating component, including a medial sideincluding a tapered bore receivable onto the tapered annular wall of thebase member; and a lateral side defining a substantially smooth,uninterrupted, convex articulating surface.

In another form thereof, the present invention provides a glenoidcomponent of a reverse shoulder system for implanting on the glenoid ofa shoulder, the glenoid component including a glenoid base including abone engaging first surface and an opposing second surface, the glenoidbase including at least one fastener receiving hole extending throughthe glenoid base from the first surface to the second surface, eachfastener receiving hole including a threaded portion proximal the secondsurface and a substantially spherical portion adjacent the threadedportion and proximal the first surface relative to the threaded portion,the glenoid base having an annular wall extending outwardly from thesecond surface; a glenosphere having an articulating surface anddefining a bore, the annular wall of the glenoid base received withinthe bore to couple the glenosphere to the glenoid base; a screw having ahead and a threaded shank and extending through the at least onefastener receiving hole and insertable into the glenoid, the head beingat least partially spherical in shape and configured to be retained inthe spherical portion of the at least one fastener receiving hole; and alocking member threadedly engaged with the threaded portion of thefastener receiving hole and abutting the head of the fastener to securethe head of the fastener in the fastener receiving hole.

In another form thereof, the present invention provides a glenoidcomponent of a shoulder prosthesis system for implanting on the glenoidof a shoulder, the glenoid component including a glenoid base includinga bone engaging first surface and an opposing second surface, theglenoid base including at least one fastener receiving hole extendingthrough the glenoid base from the first surface to the second surface,each fastener receiving hole including a threaded portion proximal thesecond surface and a substantially spherical portion adjacent thethreaded portion and proximal the first surface relative to the threadedportion; a screw having a head and a threaded shank extending throughthe at least one fastener receiving hole and insertable into theglenoid, the head being at least partially spherical in shape andconfigured to be retained in the spherical portion of the at least onefastener receiving hole; and a locking member threadedly engaged withthe threaded portion of the fastener receiving hole, the locking memberabutting the head of the screw and restricting movement of the headwithin the spherical portion of the fastener receiving hole.

In another form thereof, the present invention provides a reverseshoulder prosthesis system for the repair or replacement of a shoulderjoint, the shoulder joint including a humerus and a scapula, the reverseshoulder prosthesis system including a ball assembly mountable on thescapula, the ball assembly including a glenoid base including a boneengaging first surface and an opposing second surface, the glenoid baseincluding at least one fastener receiving hole extending through theglenoid base from the first surface to the second surface, each fastenerreceiving hole including a threaded portion proximal the second surfaceand a substantially spherical portion adjacent the threaded portion andproximal the first surface relative to the threaded portion; aglenosphere having an articulating surface and removably mounted to thebase proximal the second surface; a screw having a head and a threadedshank extending through the at least one fastener receiving hole andinsertable into the scapula, the head being at least partially sphericalin shape and configured to be retained in the spherical portion of theat least one fastener receiving hole; and a locking member threadedlyengaged with the threaded portion of the fastener receiving hole, thelocking member abutting the head of the fastener and restrictingmovement of the head within the spherical portion of the fastenerreceiving hole.

In another form thereof, the present invention provides a glenoidimplant component for use in a total shoulder arthroplasty, including aglenoid base including a bone engaging first surface and an opposingsecond surface, the glenoid base having first engagement structureextending from the second surface; a glenosphere having an articulatingsurface and second engagement structure configured to engage the firstengagement structure; and polyaxial means for anchoring the glenoidcomponent to a glenoid.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a perspective view of a “reverse” total shoulder arthroplastyimplant system according to the present invention, including a humeralcomponent and a glenoid component;

FIG. 2 is a perspective view of the humeral component of a conventionaltotal shoulder arthroplasty implant system or a hemi shoulderarthroplasty system;

FIG. 3 is a side view of the humeral stem through a medial/lateralplane, further showing an outline of the humerus;

FIG. 4 is a perspective view of the proximal end of the humeral stem;

FIG. 5 is a sectional view through a medial/lateral plane, showing theproximal end of the humeral stem;

FIG. 6A is a perspective view of the proximal end of an articulatingliner;

FIG. 6B is a perspective view of the distal end of the articulatingliner of FIG. 6A;

FIG. 7 is an exploded view of the humeral stem and articulating liner;

FIG. 8A is a partial sectional view through a medial/lateral plane,showing the connection between the humeral stem and an articulatingliner;

FIG. 8B is a partial sectional view through a medial/lateral plane,showing the connection between the humeral stem and the articulatingliner of FIG. 7;

FIG. 8C is a partial sectional view through a medial/lateral plane,showing the connection between the humeral stem and a secondarticulating liner;

FIG. 9A is a perspective view of the proximal end of a spacer;

FIG. 9B is a perspective view of the distal end of the spacer of FIG.9A;

FIG. 10 is an exploded view of the humeral stem and a spacer;

FIG. 11 is a partial sectional view through a medial/lateral plane,showing the connection between the humeral stem and the spacer of FIG.10, and further showing the connection between the spacer and anarticulating liner;

FIG. 12A is a perspective view of the distal end of an adapter insert;

FIG. 12B is a perspective view of the proximal end of the adapter insertof FIG. 12B;

FIG. 13 is an exploded view of the humeral stem, an adapter insert, anda humeral head;

FIG. 14 is a partial sectional view through a medial/lateral plane,showing the connection between the humeral stem, adapter insert, andhumeral head of FIG. 13;

FIG. 15 is a perspective view of the lateral side of a glenoid base;

FIG. 16 is a perspective view of the medial side of the glenoid base;

FIG. 17 is a sectional view of the glenoid base;

FIG. 18 is a perspective view of the medial side of the glenosphere;

FIG. 19 is a perspective view of a screw;

FIG. 20 is a first perspective view of a screw lock;

FIG. 21 is a second perspective view of a screw lock;

FIG. 22 is a sectional view through the glenoid component, showingconnection between the glenoid base, screws, and glenosphere, andfurther showing a screw and a screw head lock in a locked position onthe left and a screw and a screw head lock in an unlocked position onthe right;

FIG. 23 is partial sectional view through an anterior/posterior plane,showing the connection between the humeral stem and an articulatingliner according to a further embodiment; and

FIG. 24 is a partial sectional view through an anterior/posterior plane,showing the connection between the humeral stem and an adapter insertaccording to a further embodiment.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the invention, and suchexemplifications are not to be construed as limiting the scope of theinvention any manner.

DETAILED DESCRIPTION

As used herein, the following directional definitions apply. Anteriorand posterior mean nearer the front or nearer the rear of the body,respectively, proximal and distal mean nearer to or further from theroot of a structure, respectively, and medial and lateral mean nearerthe sagittal plane or further from the sagittal plane, respectively. Thesagittal plane is an imaginary vertical plane through the middle of thebody that divides the body into right and left halves.

Referring to FIG. 1, implant system 30 a for a “reverse” total shoulderarthroplasty is shown, which generally includes a humeral component 32adapted to be fitted within a prepared proximal end and canal of ahumerus, and a glenoid component 34 mounted to a prepared surface of theglenoid via a plurality of screws, wherein the humeral component 32articulates about the glenoid component 34 to replicate the movement ofthe natural shoulder joint. As described in further detail below,humeral component 32 generally includes humeral stem 36 and articulatingliner 38 fitted to humeral stem 36 and having a convex articulatingsurface, and glenoid component 34 generally includes a glenoid base 40and a glenosphere 42 fitted to glenoid base 40 and having a convexarticulating surface, wherein articulating liner 38 articulates aboutglenosphere 42.

Referring to FIG. 2, implant system 30 b for a conventional totalshoulder arthroplasty or a hemi shoulder arthroplasty is shown, whichgenerally includes humeral component 32 that articulates against aconventional glenoid component (not shown) in a conventional totalshoulder arthroplasty or which articulates against the intact glenoid ofthe scapula in a hemi shoulder arthroplasty. Humeral component 32generally includes humeral stem 36, an adapter insert 44, and a humeralhead 45 fitted to adapter insert 44 and having a convex articulatingsurface.

Referring to FIGS. 3-5, humeral stem 36 is shown, having proximal end 46and distal end 48. Humeral stem 36 includes head portion 50 at proximalend 46 and stem portion 52 extending toward distal end 48. In theembodiment shown is FIGS. 3-5, head portion 50 and stem portion 52 areunitarily formed as a single piece; however, head portion 50 and stemportion 52 may also be formed of separate components joined to oneanother. Humeral stem 36, as well as the other implant componentsdescribed herein, may be made of a suitable biocompatible metal, such astitanium, for example, or from other materials as described below. Headportion 50 of humeral stem is substantially enlarged with respect tostem portion 52, and flares outwardly from stem portion 52 in shapetowards proximal end 46 of humeral stein 36. As may be seen from FIG. 3,after the proximal end of the humerus is resected and the humeral canaland proximal humeral end are prepared using known instruments (notshown) and methods, stem portion 52 is received in the prepared canal ofthe humerus, and head portion 50 is received within a conically reamedportion of at the proximal end of the resected humerus.

As shown in FIGS. 4 and 5, head portion 50 includes an internal cavity54 extending into the proximal end thereof, including a first,relatively larger diameter portion 56 with an annular rib 58 and asecond, relatively smaller diameter portion defining a tapered bore 60.An annular, outer rim 62 is formed about the proximal end 46 of headportion 50 and includes an instrument seat 64 with a central bore whichmay be used to anchor and locate an impaction instrument (not shown) forimpacting humeral stem 36 into a reamed and prepared canal in thehumerus. A plurality of suture holes 66 are defined in outer rim 62 and,as shown in FIGS. 3 and 5, a suture groove 68 is disposed beneath andadjacent outer rim 62, the functions of which will be described below.

Humeral stem 36 additionally includes, toward the proximal end 46thereof, a plurality of recessed portions, best seen in FIG. 5, in whichare disposed pads or coating portions 70 of a highly porous biomaterialuseful as a bone substitute and/or cell and tissue receptive materialfor promotion of bone ingrowth to aid in the osseointegration of humeralstem 36 within the humerus. An example of such a material is producedusing Trabecular Metal™ technology available from Zimmer, Inc., ofWarsaw, Ind. Trabecular Metal™ is a trademark of Zimmer Technology, Inc.Such a material may be formed from a reticulated vitreous carbon foamsubstrate which is infiltrated and coated with a biocompatible metal,such as tantalum, etc., by a chemical vapor deposition (“CVD”) processin the manner disclosed in detail in U.S. Pat. No. 5,282,861, thedisclosure of which is incorporated herein by reference. As would beapparent to one skilled in the art, although the embodiments describedherein utilize porous tantalum, other metals such as niobium, or alloysof tantalum and niobium with one another or with other metals may alsobe used.

Referring to FIGS. 3 and 5, head portion 50 of humeral stem 36additionally includes a hub section 72 of titanium on a lateral sidethereof having a suture hole 74 through which sutures may be threaded toaid in reducing humeral fractures as needed. Suture holes 66 and suturegroove 68 of head portion 50 of humeral stem 36 may also be used by asurgeon to reconstruct the proximal humerus in the event of humeralfractures, or for the attachment of soft tissue. For example, one ormore of suture holes 66 may be used to anchor sutures wrapped aroundbone fragments of the upper humerus using suture groove 68, for example,to bring the lesser and greater tuberosities into reductioncircumferentially about humeral stem 36, or to attach soft tissuecircumferentially about humeral stem 36. Also, a surgeon may selectivelyuse one, two, three or all of suture holes 66 alone or in combinationwith each other and with suture groove 68 as needed for this purpose.Additionally, the axial clearance beneath outer rim 62 of humeral stem36 provided by suture groove 68 allows the surgeon to use one or more ofsuture holes 66 for “pull down” sutures to pull bone fragments along theaxial direction of humeral stem 36 for reduction of fractures or forattachment of soft tissue, for example.

Referring to FIG. 3, outer rim 62 at the proximal end of head portion 50of humeral stem 36 defines a substantially flat or planar surface which,as shown, is disposed substantially along a resection cut line L₂-L₂along which a surgeon makes a resection cut to resect the proximalhumerus H when humeral stem 36 is implanted during a total or hemishoulder arthroplasty. A first neck angle α is defined in amedial/lateral plane between the surface of outer rim 62 along resectioncut line L₂-L₂, and the longitudinal axis L₁-L₁ of humeral stem 36. Neckangle α may be as little as about 35, 40, or 45 degrees, and may be asgreat as about 50 or 55 degrees when humeral stem 36 is used in aconventional shoulder arthroplasty or in a hemi arthroplasty, asdescribed below. In the embodiment of FIG. 3 and in FIGS. 8B and 8Cdiscussed below, neck angle α is about 53 degrees. Further, as alsodescribed below, an articulating liner may be used to provide a greaterneck angle with respect to longitudinal axis L₁-L₁ of humeral stem 36which is more suited to a “reverse” shoulder arthroplasty.

Referring to FIGS. 6A and 6B, proximal and distal perspective viewsrespectively, of an articulating liner 38 for fitting to humeral stem 36are shown, including a body 76 which may be formed of a single, integralpiece of ultra high molecular weight polyethylene (“UHMWPE”), forexample. The proximal end of articulating liner 38 includes a convexarticulating surface 78 for articulating against glenosphere 42 (FIG. 1)of glenoid component 34. The distal end of articulating liner 38includes a plurality of spring fingers 80 spaced therearound and a post82 which may be non-tapered to provide an interference fit withintapered bore 60 of humeral stem 36. Articulating liner 38 furtherincludes a plurality of recesses 84 disposed about the outer peripheryof body 76 for providing clearance for accessing suture holes 66 ofhumeral stem 36 when articulating liner 38 is attached to humeral stem36 in the manner described below.

Referring additionally to FIGS. 7 and 8, articulating liner 38 isattachable to humeral stem 36 by using an impaction instrument (notshown) which may include a first portion fitting within the cavitydefined by articulating surface 78 and a second, prong-type portioninsertable through notch 86 in the outer periphery of body 76 ofarticulating liner 38 and through the bore of instrument seat 64 ofhumeral stem 36 to rotationally locate articulating liner 38 withrespect to humeral stem 36, with post 82 of articulating liner 38received within tapered bore 60 of humeral stem 36 by an interferencefit. Thereafter, articulating liner 38 is impacted into internal cavity54 of humeral stem 36 until spring fingers 80 of articulating liner 38resiliently engage behind annular rib 58 of humeral stem 36 to therebyaxially lock articulating liner 38 with respect to humeral stem 36, withrotation of articulating liner 38 with respect to humeral stem 36prevented by the engagement of instrument seat 64 of humeral stem 36within notch 86 of articulating liner 38.

As shown in FIGS. 6A-8C, articulating liner 38 is substantiallywedge-shaped, having an annular lower surface 83 in abutment with outerrim 62 of head portion 50 of humeral stem 36 as shown in FIGS. 8B and8C, and an annular upper surface 85 opposite lower surface 83. As shownin FIGS. 8B and 8C, lower and upper surfaces 83 and 85 together definean angle γ therebetween in a medial/lateral plane which may be as smallas about 1 or 5 degrees, or may be as large as about 15, 30, or 35degrees, or may be sized at any one degree increment therebetween, forexample. In the embodiment of FIG. 8B, a first articulating liner 38 adefines an angle γ of about 7 degrees and, in the embodiment of FIG. 8C,a second articulating liner 38 b defines an angle γ of about 12 degrees.Further details of first and second articulating liners 38 a and 38 bare discussed below. When an articulating liner 38 a or 38 b is securedto head portion 50 of humeral stem 36 in the manner described above, theupper surface 85 of the articulating liner defines a second neck angle βwith respect to longitudinal axis L₁-L₁ of humeral stem 36 or, statedanother way, the first neck angle α, between longitudinal axis L₁-L₁ ofhumeral stem 36 and outer rim 62 along resection cut line L₂-L₂, and theangle γ of articulating liner 38 combine to define second neck angle β.As with first neck angle α and angle γ of articulating liner 38, secondneck angle β is in a medial/lateral plane. Second neck angle β may be assmall as about 55 or 60 degrees, or may be as large as about 65 or 70degrees when humeral stem 36 is configured for a “reverse” shoulderarthroplasty, and the articulating liner 38 may be selected from aplurality of articulating liners 38 having varying angles γ to provideproper stability for the shoulder joint. In the embodiment of FIG. 8B,second neck angle β is about 60 degrees and in the embodiment of FIG. 8Csecond neck angle β is about 65 degrees.

Articulating liner 38 may be selected by a surgeon from a plurality ofdifferently-sized articulating liners, having varying size diameters andheights, for example, to provide a properly sized articulating liner fora given patient anatomy and/or joint reconstruction need. Additionally,a plurality of trial or provisional articulating liners (not shown) maybe provided with the present implant system, which lack spring fingers80 and/or post 82 but otherwise are substantially identical to theimplanted articulating liner 38. In this manner, a surgeon may use suchprovisional articulating liners during the arthroplasty procedure todetermine the correct size of articulating liner to be implanted,followed by selecting the desired articulating liner and securing sameto humeral stem 36 in the manner described above.

Referring to FIGS. 8B and 8C, two differently-sized articulating liners38 a and 38 b are shown, which are structurally identical except for thediameter of articulating surfaces 78 a and 78 b thereof. In oneembodiment, articulating liner 38 a has an articulating surface 78 awith a diameter D₁ of 36 mm, and articulating liner 38 b has anarticulating surface 78 b with a diameter D₂ of 40 mm. However, thediameters of the articulating liners 38 may be as small as about 30 mm,32 mm, or 34 mm, or may be as large about 50 mm, 55 mm, or 60 mm, or maybe sized at any one degree increment therebetween, for example.Articulating liner 38 a may typically be used in most patients; however,articulating liner 38 b may be used in relatively larger patients, or inother cases where a greater diameter articulating surface may be desiredsuch as, for example to provide greater joint stability. Advantageously,because the above-described structure by which articulating liners 38 aand 38 b are secured to head portion 50 of humeral stem 36 is identical,a surgeon may intra-operatively select an appropriate articulating linerfrom articulating liner 38 a, articulating liner 38 b, or anarticulating liner having a differently sized or differently dimensionedarticulating surface (not shown) based on the anatomical needs of aparticular patient. Thus, a series of articulating liners may beprovided, having varying articulating surface diameters or otherdimensions, which are compatible with humeral stem 36.

Optionally, spacers 90 (FIGS. 9A-11) of various size, described below,may be used to provide increased tension on the shoulder joint whenneeded in the event that the height of articulating liner 38 is notsufficient to provide such tension. Referring to FIGS. 9A and 9B,proximal and distal perspective views, respectively, of a spacer 90 areshown, including a body 92 which may be formed of titanium, for example.The proximal end of spacer 90 includes internal cavity 94 having anannular rib 96 and a bore 98 which dimensionally replicate the internalcavity 54 of humeral stem 36 and in particular, the annular rib 58 andbore 60 of humeral stem 36, described above. Additionally, spacer 90includes instrument seat 100 replicating instrument seat 64 of humeralstem 36, described above. The distal end of spacer 90 includes taperedstem 102 for lockably fitting within tapered bore 60 of humeral stem 36.Body 92 of spacer 90 includes a plurality of recesses 104 disposed aboutan outer periphery thereof for providing clearance for accessing sutureholes 66 of humeral stem 36 when spacer 90 is attached to humeral stem36 in the manner described below.

In use, referring additionally to FIGS. 10 and 11, spacer 90 may befitted to humeral stem 36 using a suitable instrument (not shown) insubstantially the same manner as articulating liner 38 described above,with tapered stem 102 of spacer 90 providing a tapered lock fit withintapered bore 60 of humeral stem 36, and with relative rotation betweenspacer 90 and humeral stem 36 prevented by engagement of instrument seat64 of humeral stem 36 within notch 106 (FIG. 9B) of spacer 90 disposedopposite seat 100 of spacer 90. Thereafter, a selected articulatingliner 38 may be attached within internal cavity 94 of spacer 90 in thesame manner as that described above with respect to the attachment ofarticulating liner 38 to humeral stem 36, namely, by engaging springfingers 80 of articulating liner 38 with annular rib 96 of spacer 90 andreceipt of post 82 of articulating liner 38 within bore 98 of spacer 90.Spacer 90 also includes a threaded central bore 108 that may be used forthreading receipt of a threaded end of a retrieval instrument (notshown) used to remove spacer 90 from humeral stem 36 whereby, uponthreading of the threaded end of the retrieval instrument throughthreaded bore 108, the threaded end will bottom out against the bottomof tapered bore 60 of humeral stem 36 to disengage spacer 90 fromhumeral stem 36.

Referring to FIGS. 12A and 12B, distal and proximal views of adapterinsert 44 are shown, which may be used with humeral stem 36 to providean interface with humeral head 45 to configure humeral stem 36 for usein a conventional total shoulder arthroplasty or a hemi shoulderarthroplasty. The proximal end of adapter insert 44 includes a firsttapered stem 110 and the distal end of adapter insert 44 includes asecond tapered stem 112, with a central bore 114 extending therethrough.Referring additionally to FIGS. 13 and 14, when the distal end ofadapter insert 44 is received within internal cavity 54 of humeral stem36, second tapered stem 112 of adapter insert 44 is lockingly fittablewithin tapered bore 60 of humeral stem 36. Thereafter, humeral head 45,which includes a distal tapered bore 116 and proximal convexarticulating surface 118 may be fitted onto first tapered stem 110 ofadapter insert 44 to complete the humeral assembly. In use, as describedabove, convex articulating surface 118 of humeral head 45 articulatesagainst a conventional glenoid component (not shown) in a conventionaltotal shoulder arthroplasty, or articulates against the intact glenoidof the scapula in a hemi shoulder arthroplasty. Adapter insert 44additionally includes thread 120 (FIG. 12A) within central bore 114 toenable adapter insert 44 to be removed from humeral stem 36 using athreaded retrieval instrument (not shown) analogous to the mannerdescribed above with respect to the removal of spacer 90 from humeralstem 36.

As discussed below, the articulating liners and the adapter inserts ofthe present shoulder implant system may also include an anteversion orretroversion feature. Referring to FIGS. 23 and 24, further embodimentsof an articulating liner and an adapter insert are shown, which are eachangled in an anterior/posterior plane with respect to the longitudinalaxis L₁-L₁ of humeral stem 36 to provide anteversion or retroversion.

Referring to FIG. 23, an articulating liner 38 c is shown attached tohumeral stem 36 which, except as described below, is identical toarticulating liner 38 described above. Body 76 of articulating liner 38c includes a concave articulating surface 78 c which is oriented at anangle Δ in an anterior/posterior plane with respect to longitudinal axisL₁-L₁ of humeral stem 36. Specifically, a line L₃-L₃, which isperpendicular to articulating surface 78 c and passes through the centerthereof, defines angle Δ with respect to longitudinal axis L₁-L₁ ofhumeral stein 36. Angle Δ may define an anterior-facing orientation ofarticulating surface 78 c for anteversion or, as shown in FIG. 23, angleΔ may define a posterior-facing orientation of articulating surface 78 cfor retroversion. Angle Δ may be as small as about 1, 5, or 10 degrees,or may as large as about 20, 25, or 30 degrees, or may be sized at anyone degree increment therebetween, for example. In the embodiment ofFIG. 23, angle Δ is about 20 degrees. Additionally, as shown in FIG. 23,the articulating liners 38 disclosed herein may include both theforegoing anteversion or retroversion angle Δ in an anterior/posteriorplane with respect to longitudinal axis L₁-L₁ of humeral stem 36, aswell as the above-described angle γ in a medial/lateral plane withrespect to the longitudinal axis L₁-L₁ of humeral stem 36. In thismanner, articulating liner 38 c can be used to provide anteversion orretroversion in a “reverse” total shoulder arthroplasty.

Referring to FIG. 24, adapter insert 44 a is shown attached to humeralstem 36 which, except as described below, is identical to adapter insert44 described above. Adapter insert 44 a includes an angled body portion111 which positions first tapered stem 110 of adapter insert 44 a at anangle Δ in an anterior/posterior plane with respect to longitudinal axisL₁-L₁ of humeral stem 36. Specifically, a line L₃-L₃, which extendsalong the longitudinal axis of adapter insert 44 a and tapered stem 110,defines angle Δ with respect to longitudinal axis L₁-L₁ of humeral stem36. Angle Δ may define an anterior-facing orientation of first taperedstem 110 for anteversion or, as shown in FIG. 24, angle Δ may define aposterior-facing orientation of first tapered stem 110 for retroversion.Angle Δ may be as small as about 1, 5, or 10 degrees, or may as large asabout 20, 25, or 30 degrees, or may be sized at any one degree incrementtherebetween, for example. In the embodiment of FIG. 23, angle Δ isabout 20 degrees. Humeral head 45, having convex articulating surface118, is mounted to first tapered stem 110 of adapter insert 44 a in themanner described above, and is oriented according to the anteversion orretroversion angle defined by adapter insert 44 a. Additionally, similarto the articulating liners 38 disclosed herein, adapter insert 44 a mayinclude both the foregoing anteversion or retroversion angle Δ in ananterior/posterior plane with respect to longitudinal axis L₁-L₁ ofhumeral stem 36, as well as an angle in a medial/lateral plane withrespect to the longitudinal axis L₁-L₁ of humeral stem 36. In thismanner, adapter insert 44 a can be used to provide anteversion orretroversion in a conventional total shoulder arthroplasty or in a hemishoulder arthroplasty.

Advantageously, humeral stem 36 provides a humeral component whichserves as a universal humeral implant platform that may be used with thevarious modular components in the manner described above to configurehumeral stem 36 for use in a “reverse” total shoulder arthroplasty, aconventional total shoulder arthroplasty, or a hemi shoulderarthroplasty. Thus, once the humeral stem 36 is implanted within theproximal humerus as shown in FIG. 3, the humeral stem 36 may beconfigured for a “reverse” total shoulder arthroplasty as shown in FIGS.1 and 6A-11, or a conventional total shoulder arthroplasty or hemishoulder arthroplasty as shown in FIGS. 2 and 12A-14 according topatient needs by using the components described above.

Also, once implanted, humeral stem 36 may remain implanted throughoutany necessary revision procedures, allowing a surgeon to perform anyrevisions as needed by replacing one more of the various modularcomponents described above without the need to replace humeral stem 36itself. For example, if a patient initially has a hemi shoulderarthroplasty and later is in need of a revision to receive a “reverse”total shoulder arthroplasty, humeral head 45 is removed, followed byadapter insert 44. Thereafter, an articulating liner 38 and optionally,a spacer 90, are attached to humeral stem 36 in the manner describedabove without the need to remove humeral stem 36 from the patient'shumerus. A similar procedure may be used to convert a conventional totalshoulder arthroplasty to a “reverse” total shoulder arthroplasty.

One particular advantage of humeral stem 36 is that the proximal surfacethereof lies substantially along the resection cut line L₂-L₂ of theresected humerus as discussed above. Thus, the various modularcomponents disclosed herein may be attached, removed, and/or replacedonto the implanted humeral stem 36 above the resection cut line L₂-L₂without the need for removing bone around the proximal humerus H and/orreplacing or modifying the location of the implanted humeral stem 36 inthe humerus H.

Referring to FIGS. 15-22, glenoid component 34 (FIG. 22) is shown, whichgenerally includes a glenoid base 40, shown in FIGS. 15-17 and 22, andglenosphere 42, shown in FIGS. 18 and 22. Referring to FIGS. 15-17,glenoid base 40 includes a body 130 which may be made of a suitablebiocompatible metal such as titanium, for example, and includes stemportion 132 (FIG. 17) projecting from a medial side thereof, and atapered annular wall 134 projecting from a lateral side thereof. Themedial side of body 130 of glenoid base 40, including stem portion 132,may include a pad or coating portion 135 of the highly porousbiomaterial described above, produced using Trabecular Metal™ technologyavailable from Zimmer, Inc., of Warsaw, Ind., to promote bone ingrowthfrom the glenoid into and around glenoid base 40 to therebyosseointegrate glenoid base 40 with the glenoid. Typically, the glenoidis prepared for attachment of glenoid component 34 by preparing a borein the glenoid for receipt of stem portion 132 of glenoid body 130, andby reaming the glenoid with a reamer (not shown) to prepare asubstantially flat, planar surface on the glenoid to which thesubstantially flat, planar medial side of body 130 may be fitted, asdescribed below.

Body 130 of glenoid base 40 includes a pair of bores 136 therethroughwhich, as best shown in FIG. 17, include first, threaded portions 138and second portions 140 which are tapered to open outwardly toward themedial side of glenoid base 40. Bores 136 additionally include screwhead seats 142 located between first and second portions 138 and 140 ofbores 136. As shown, screw head seats 142 have an at least partiallyspherical shape, but may also have an angled or tapered profile. Tosecure glenoid base 40 to the glenoid, a pair of polyaxial screws 144are provided, shown in FIG. 19, each including a substantially sphericalhead 146 with tool engagement structure, such as a polygonal fitting148, and a threaded shank 150. Screw locks 152, shown in FIGS. 20 and21, are also provided which, as described below, cooperate with threadedportions 138 of bores 136 and with heads 146 of screws 144 to lock thepositions of screws 144. Each screw lock 152 generally includes anexternal thread 154, a semi-spherical concave seat 156, and instrumentengagement structure such as a polygonal fitting 158.

Referring to FIG. 22, glenoid base 40 is shown with a screw 144 andscrew head lock 152 in a locked position on the left and a screw 144 andscrew head lock 152 in an unlocked position on the right. To secureglenoid base 40 to the prepared glenoid, each screw 144 is insertedusing a suitable instrument (not shown) through a respective bore 136 inbody 130 and is threaded into a pre-tapped bore in the glenoid. Taperedsecond portions 140 of bores 136 accommodate polyaxial positioning ofscrews 144 up to an angle of 30° from the longitudinal axis of glenoidbase 40 as defined along stem portion 132 thereof. Advantageously, theability of glenoid base 40 to accommodate polyaxial positioning ofscrews 144 allows the surgeon to determine optimum angles of screws 144needed to conform to the anatomy of the patient and/or to mosteffectively take advantage of available bone stock to anchor glenoidbase 40 to the glenoid. Thereafter, referring to the left of FIG. 22,screw locks 152 are threaded into threaded first portions 138 of bores136 using a suitable instrument (not shown) to firmly engage seats 156of screw head locks 152 against heads 146 of screws 144, thereby firmlypressing screw heads 146 against seats 142 within bores 136 to lockingscrew heads 146 in a selected fixed position and in turn to fix thepositions of screws 144 with respect to glenoid base 40.

Advantageously, as may be seen in FIGS. 17 and 22, because body 130 ofglenoid base 40 includes tapered second portions 140 of bores 136 toaccommodate polyaxial positioning of screws 144, with screw seats 142recessed into the medial side of body 130 of glenoid base 40, glenoidbase 40 may include a substantially planar medial side 160, with taperedsecond portions 140 of bores 136 accommodating polyaxial positioning ofscrews 144. The planar medial side 160 of glenoid base 40 allows glenoidbase 40 to be seated against a planar surface of the glenoid which maybe prepared with a planar reamer (not shown), and eliminates the needfor boss portions or other protuberances projecting from the medial sideof glenoid base 40 to accommodate polyaxial positioning of screws 144,which would require additional glenoid preparation steps to accommodate.

Referring to FIGS. 18 and 22, glenosphere 42 generally includes a medialside having a tapered interior bore 162 extending therein, which may bealigned with a longitudinal axis of glenosphere 42 or may be offset withrespect to the longitudinal axis of glenosphere 42. Glenosphere 42additionally includes a lateral side having a convex articulatingsurface 164. Glenosphere 42 may be provided in a variety of differentsizes, such as with varying diameters, varying heights, and varyingoffsets for internal bore 162 to enable a surgeon to select an optimalglenosphere needed for the anatomy of a particular patient. Theglenosphere is fitted onto glenoid base 40 by lockingly fitting taperedbore 162 of glenosphere 42 onto the cooperatively tapered annular wall134 of glenoid base 40. Advantageously, the foregoing attachment betweenbore 162 of glenosphere 42 and annular wall 134 of glenoid base 40allows glenosphere 42 to have a substantially smooth, uninterruptedarticulating surface 164 which lacks an opening therein for receipt of afastener, for example.

While this invention has been described as having a preferred design,the present invention can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

What is claimed is:
 1. A humeral implant component for use in a totalshoulder arthroplasty or a hemi shoulder arthroplasty, comprising: astem portion extending toward a distal end thereof; a head portion at aproximal end thereof, said head portion including an internal cavityhaving first engagement structure and a first tapered bore; and a secondcomponent received within said internal cavity and including a firststem received within said first tapered bore.